The invention concerns a telescoping shaft.
Telescoping shafts are generally a part of a drive shaft with universal joints at both ends, and usually have a spline shaft profile between the inner shaft and the hollow shaft. Such a shaft is known, e.g., from German Utility Model 69 08 115. The axial displaceability of the two shaft sections is of the order of the diameter of the driving flange.
Since the axial displacement is a pure sliding movment, in a tooth contour with close tolerances, considerable energy is required for the displacement, even when friction and wear are reduced by a special coating. Low surface pressure requires large friction surfaces and a large unit for the longitudinal compensation.
Another telescoping shaft known from DOS 25 22 108 utilizes an inner shaft to reduce the axial force required for the displacement, which is provided with three runways designed as radial grooves, in which roll radially arranged rollers which are rotatably mounted on the inner surface of the hollow shaft.
The frictional resistance can be substantially reduced by this design, but it still can exceed the low axial force desired in certain applications. A telescoping shaft of the above-described type is intended for installations which are subject to considerable axial displacement during operation under load. For telescopic shafts which only cover small displacements, this type of shaft is too elaborate.
A toggle joint clutch is known (German Utility Model 1,977,640), wherein toggle joints are used for the transmission of the torque, which transmit the circumferential force in pairs in each direction of rotation from the driving- to the driven shaft. The arrangement of the toggle joints ensures a centric but not buckling-resistant guidance of the two clutch halves, that is, elastic spherical joints allow the toggle joints cardanic mobility of the shaft ends. Axial movements of the shafts are possible in this clutch only within the framework of the radial elasticity of the spherical elastic joint, due to the symmetrical arrangement of the guide rods. This clutch can perform its function only due to the elasticity of the spherical joints.